User user91132

29 votes

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When is $\ker AB = \ker A + \ker B$?

answered Nov 5, 2011 at 12:10

21 votes

How to memorise (understand) Nakayama's lemma and its corollaries?

answered Apr 13, 2011 at 8:14

17 votes

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Explicit ring of differential operators for polynomial algebras over the integers?

answered Feb 28, 2011 at 9:57

13 votes

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Annihilators in Matrix Rings

answered Jul 13, 2012 at 22:33

13 votes

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Non-commutative reduced rings of order $p^2$

answered Sep 9, 2013 at 20:22

12 votes

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non commutative polynomial which is zero for all matrix evaluation

answered Nov 27, 2015 at 7:12

11 votes

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For $G=\mathbb{Z}^2\rtimes \mathbb{Z}$, $Spec(\mathbb{Z}G)$=?

answered Sep 1, 2013 at 15:56

10 votes

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$\mathcal{D}$-modules of level m

answered Sep 13, 2012 at 22:35

10 votes

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How to work with co-multiplication?

answered Feb 28, 2011 at 11:46

8 votes

ad-nilpotent degree of a nilpotent Lie Algebra

answered May 20, 2011 at 12:51

8 votes

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Projective dimension of simple module

answered Aug 12, 2012 at 10:34

7 votes

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ad (A^n) is a polynomial in ad A ?

answered Jul 1, 2012 at 10:14

7 votes

Is a polynomial ring integral over this subring ?

answered Oct 21, 2012 at 19:50

7 votes

Reference for a Maschke lemma for crossed products

answered Apr 18, 2012 at 4:02

7 votes

What would you want on a Lie theory cheat poster?

answered Apr 26, 2011 at 22:10

7 votes

When is a restricted enveloping algebra a domain? A finitely generated domain?

answered May 10, 2011 at 11:02

7 votes

Ideals of $U(\mathrm{gl}(n,\mathbb{C}))$ and their intersection with center

answered Jan 3, 2016 at 13:04

7 votes

Applications of Chevalley Restriction Theorem

answered May 31, 2013 at 20:50

7 votes

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Noncommutative group of invertible ideals of a ring

answered Sep 23, 2015 at 21:58

6 votes

Galois extension of a semi-local ring

answered Sep 29, 2012 at 9:03

6 votes

Are submodules of free modules free?

answered Dec 29, 2010 at 11:45

6 votes

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Center of universal enveloping algebra of nilpotent lie algebra

answered Apr 3, 2012 at 23:24

5 votes

Center of p-groups

answered Sep 14, 2012 at 14:01

5 votes

Jacobson radical = intersection of all maximal two-sided ideals

answered Dec 27, 2010 at 21:37

4 votes

Conjugacy for p-adic matrices of finite order II

answered Aug 9, 2011 at 20:25

4 votes

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Prime ideals in maximal orders (1- and 2-sided)

answered Feb 1, 2012 at 18:21

4 votes

Projectivity of one Tate algebra over another

answered Feb 16, 2012 at 23:09

4 votes

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Completion and Tensor Product of Algebras

answered Jul 18, 2012 at 19:21

4 votes

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Descriptions of projectives (injectives) in category of D-modules

answered Feb 25, 2011 at 22:09

4 votes

Borel–Weil theorem - reference request

answered Feb 28, 2012 at 19:35

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51 Answers

When is $\ker AB = \ker A + \ker B$?

How to memorise (understand) Nakayama's lemma and its corollaries?

Explicit ring of differential operators for polynomial algebras over the integers?

Annihilators in Matrix Rings

Non-commutative reduced rings of order $p^2$

non commutative polynomial which is zero for all matrix evaluation

For $G=\mathbb{Z}^2\rtimes \mathbb{Z}$, $Spec(\mathbb{Z}G)$=?

$\mathcal{D}$-modules of level m

How to work with co-multiplication?

ad-nilpotent degree of a nilpotent Lie Algebra

Projective dimension of simple module

ad (A^n) is a polynomial in ad A ?

Is a polynomial ring integral over this subring ?

Reference for a Maschke lemma for crossed products

What would you want on a Lie theory cheat poster?

When is a restricted enveloping algebra a domain? A finitely generated domain?

Ideals of $U(\mathrm{gl}(n,\mathbb{C}))$ and their intersection with center

Applications of Chevalley Restriction Theorem

Noncommutative group of invertible ideals of a ring

Galois extension of a semi-local ring

Are submodules of free modules free?

Center of universal enveloping algebra of nilpotent lie algebra

Center of p-groups

Jacobson radical = intersection of all maximal two-sided ideals

Conjugacy for p-adic matrices of finite order II

Prime ideals in maximal orders (1- and 2-sided)

Projectivity of one Tate algebra over another

Completion and Tensor Product of Algebras

Descriptions of projectives (injectives) in category of D-modules

Borel–Weil theorem - reference request